Default cm installer not working

Ok so i have been trying to use cyanogenmod installer with my phone, it gets as far as download mode then i get an error messege saying "we couldn't talk to your phone". i have tried the installer on 3 computers, 2 running windows 7 and 1 running windows 8. I have also tried to install the drivers by using zadig but on all 3 pc's i get "the driver installation failed". what could be causing this? ...Sam

P.S sorry if i posted this in the wrong section.